Biased passages for turbomachinery

ABSTRACT

Turbomachines having one or more flow guiding features designed to increase the performance of the turbomachine (3400, 3700, 4000, 4800). In some examples, flow guiding features are designed and configured to bias a circumferential pressure distribution at a diffuser inlet (2210, 2310, 3410, 4204, 4810, 5208, 808) toward circumferential uniformity, otherwise account for such low-frequency spatial pressure variations, increase the controllability of spatial flow field variations, or modifying flow field variations, etc. In some examples, a diffuser (1000, 1100, 1200, 1300, 1500, 1600, 1700, 1800, 1900, 2000, 2100, 2200, 2300, 2400, 2500, 2600, 2700, 2800, 2900, 3000, 3200, 3300, 3404, 4004, 4700, 4804, 5000, 5200, 602, 800, 900) having a row (802) of vanes (2102, 5218, 802) that include a plurality of first vanes (1002, 1102, 1202, 1302, 1402, 1502, 1602, 1702, 1802, 1902, 2002, 2204, 2304, 2402, 2502, 2602, 2702, 2802, 2902, 3002, 3102, 3202, 3302, 812, 902) and at least one second vane (1004, 1104, 1204, 1304, 1404, 1504, 1604A, 1604B, 2206, 2306, 2404, 2504, 2604, 2704, 2804, 2904A, 2904B, 814, 908) having a different characteristic than the first vanes (1002, 1102, 1202, 1302, 1402, 1502, 1602, 1702, 1802, 1902, 2002, 2204, 2304, 2402, 2502, 2602, 2702, 2802, 2902, 3002, 3102, 3202, 3302, 812, 902) are disclosed. In some examples, diffusers (1100, 1900, 2400, 2500) having an aperiodic section (2412, 2512, 2612, 2712, 2812) including one or more biased passages (1006, 1106, 1206, 1306, 1506A, 1606A, 1606B, 2406, 2506, 2606, 2706, 2806A, 2906A, 3206, 4510, 816) for biasing a flow field are disclosed. And in some examples, turbomachines having flowwise elongate recesses (4706) in one or both of a hub (3407, 4002, 4504, 4807, 5002, 5204, 804, 904) and shroud (3406, 4502, 4708, 4712, 4806, 5004, 5202, 806, 906) surface are disclosed.

RELATED APPLICATION DATA

This application claims the benefit of priority of U.S. ProvisionalPatent Application Ser. No. 62/155,341, filed Apr. 30, 2015, and titled“Biased Passage(s) Flow Devices For Turbomachinery,” and U.S.Provisional Patent Application Ser. No. 62/243,415, filed Oct. 19, 2015,and titled “Methods For Designing Turbomachines To Account ForNon-Uniform Pressures At Diffuser Inlet And Associated Structures AndDevices”. Each of these applications is incorporated by reference hereinin its entirety.

FIELD OF THE INVENTION

The present invention generally relates to the field of turbomachinery.In particular, the present invention is directed to biased passages forturbomachinery.

BACKGROUND

A wide variety of diffuser types for centrifugal pump and compressorstages have been employed over the past several decades. In some cases,a good impeller has been designed first, and then a good diffuser isdesigned next, or the two elements are designed concurrently.Regardless, essentially all past work has been based on thequasi-steady/axisymmetric assumption of diffuser inlet flow which hastypically been treated simply as a one-dimensional (1D) velocitytriangle model for preliminary design. Much of these assumptions carryover even with computational fluid dynamic (CFD) models used today. Ithas typically been assumed, at some level, that the flow leaving animpeller, regardless of the number of blades, and then entering thediffuser, again regardless of the number of vanes, is essentiallyperiodic and axisymmetric, and completely and uniformly fills eachdiffuser passage.

SUMMARY OF THE DISCLOSURE

In one implementation, the present disclosure is directed to a diffuserfor a turbomachine that includes a plurality of diffuser passageslocated around a circumference of the diffuser for receiving a flowfield having a circumferential pressure distribution; wherein thediffuser passages include at least one periodic section and at least oneaperiodic section, the at least one aperiodic section including at leastone biased passage that is located, configured, and dimensioned to biasthe circumferential pressure distribution toward circumferentialuniformity.

In another implementation, the present disclosure is directed to adiffuser that includes a plurality of first vanes arranged in a rowaround a portion of a circumference of the diffuser, each of the firstvanes spaced a first circumferential distance from an adjacent firstvane; and at least one second vane located between ones of the firstvanes, the at least one second vane having a different characteristicthan the first vanes, the different characteristic resulting in a biasedpassage proximate the at least one second vane for biasing acircumferential pressure distribution of a flow field entering thediffuser toward a circumferentially uniform pressure distribution.

In yet another implementation, the present disclosure is directed to adiffuser that includes a hub and a shroud; a plurality of first vanesextending from the hub to the shroud and arranged in a row around aportion of a circumference of the diffuser; and at least one second vanelocated between ones of the first vanes, the at least one second vaneextending from the hub to the shroud and having a differentcharacteristic than the first vanes.

In still another implementation, the present disclosure is directed to adiffuser that includes a hub and a shroud; and a plurality of vanegroupings each including at least two vanes, each of the at least twovanes having a different characteristic than other ones of the at leasttwo vanes.

In yet another implementation, the present disclosure is directed to amethod of designing a diffuser having an inlet and a plurality of vanesto reduce a circumferential pressure variation proximate the inlet, thepressure variation having a primary spatial frequency that is less thana spatial frequency of the vanes. The method includes providing aplurality of diffuser passages each having an inlet and located around acircumference of the diffuser; and locating at least one biased diffuserpassage between ones of the plurality of diffuser passages, the biaseddiffuser passage having a different cross-sectional area than theplurality of diffuser passages for minimizing the circumferentialpressure variation at the inlets of the plurality of diffuser passages.

In still yet another implementation, the present disclosure is directedto a method of designing a diffuser that includes developing acomputational model of an axisymmetric diffuser; calculating aperformance of the diffuser when a circumferential pressure distributionhaving a time averaged low-frequency circumferential variation ispresent at an inlet to the diffuser; modifying the computational modelto add at least one biased flow passage to the diffuser; calculating aperformance of the modified diffuser; and comparing the diffuserperformance from the two calculating steps to determine if the biasedflow passage improved diffuser performance.

In another implementation, the present disclosure is directed to amethod of designing a diffuser, that includes measuring acircumferential pressure distribution at an inlet to a first diffuserhaving periodic diffuser passages; replacing the first diffuser with asecond diffuser having at least one aperiodic section with at least onebiased diffuser passage; measuring a circumferential pressuredistribution at an inlet to the second diffuser; and comparing thepressure distributions from the two measuring steps to determine whetherthe second diffuser reduced an undesired variation in a magnitude of themeasured circumferential pressure distribution by a predeterminedamount.

In yet another implementation, the present disclosure is directed to avaneless diffuser, that includes an inlet and an exit; a hub surface anda shroud surface each extending between the inlet and the exit; and aplurality of flowwise recesses in at least one of the hub and shroudsurfaces, the plurality of recess being aperiodic.

In still another implementation, the present disclosure is directed to adiffuser for a turbomachine that includes a plurality of diffuserpassages located around a circumference of the diffuser for receiving aflow field, wherein the flow field has a circumferential pressuredistribution; wherein the diffuser passages include a first set ofpassages each having a first effective cross-sectional area distributionalong a flow-wise direction and at least one biased passage having asecond effective cross-sectional area distribution along the flowwisedirection, the first and second effective cross-sectional areadistributions being different, the at least one biased passage located,configured, and dimensioned to bias the circumferential pressuredistribution toward circumferential uniformity.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purpose of illustrating the invention, the drawings show aspectsof one or more embodiments of the invention. However, it should beunderstood that the present invention is not limited to the precisearrangements and instrumentalities shown in the drawings, wherein:

FIG. 1 shows circumferential static pressure measurements at impellertip/diffuser inlet for a flat plate diffuser operably coupled to acentrifugal compressor impeller operating at 120,000 RPM;

FIG. 2 is a subset of the data from FIG. 1;

FIG. 3 shows circumferential static pressure measurements for the samemachine as FIGS. 1 and 2, but operating at 135,000 RPM;

FIG. 4 shows circumferential static pressure measurements for a channeldiffuser operably coupled to a centrifugal compressor impeller operatingat 100,000 RPM;

FIG. 5 shows circumferential static pressure measurements for the samemachine as FIG. 4, but operating at 135,000 RPM;

FIG. 6 shows a prior art volute;

FIG. 7 shows circumferential pressure measurements for a compressor orpunp with a downstream volute;

FIG. 8 shows a flat plate diffuser with a biased passage formed by apartial height vane affixed to a shroud surface;

FIG. 9 shows a flat plate diffuser with a biased passage formed by apartial height vane affixed to a hub surface;

FIG. 10 shows a flat plate diffuser with a biased passage formed by asecond vane having an alternate flowwise location and stagger angle;

FIG. 11 shows a flat plate diffuser with a biased passage formed by asecond vane having an alternate thickness;

FIG. 12 shows a flat plate diffuser with a biased passage formed by asecond vane having an alternate thickness;

FIG. 13 shows a flat plate diffuser with a biased passage formed by asecond vane having an alternate chord length;

FIG. 14 shows a flat plate diffuser with a biased passage formed by asecond vane having an alternate chord length and stagger angle;

FIG. 15 shows a flat plate diffuser with a biased passage formed by asecond vane having an alternate pitch;

FIG. 16 shows a flat plate diffuser with a biased passage formed bysecond vanes having alternate chord length and thickness;

FIG. 17 shows a flat plate diffuser having a row of vanes that includefirst and second vanes, the second vanes having an alternate chordlength;

FIG. 18 shows a flat plate diffuser having a row of vanes that includefirst and second vanes, the second vanes having an alternate chordlength and leading edge location;

FIG. 19 shows a flat plate diffuser having a row of vanes that includefirst and second vanes, the second vanes having an alternate staggerangle;

FIG. 20 shows a flat plate diffuser having a row of vanes that includefirst and second vanes, the first vanes having an alternate staggerangle;

FIG. 21 shows a prior art channel diffuser;

FIG. 22 shows a channel diffuser having first and second vanes, thesecond vanes being flat plate vanes;

FIG. 23 shows a channel diffuser having first and second vanes, thesecond vanes being flat plate vanes;

FIG. 24 shows a channel diffuser with a biased passage formed by asecond vane having alternate wedge angle;

FIG. 25 shows a channel diffuser with a biased passage formed by asecond vane having alternate wedge angle;

FIG. 26 shows a channel diffuser with a biased passage formed by asecond vane having alternate chord length;

FIG. 27 shows a channel diffuser with a biased passage formed by asecond vane having alternate stagger angle;

FIG. 28 shows a channel diffuser with a biased passage formed by asecond vane having alternate pitch;

FIG. 29 shows a channel diffuser with a biased passage formed by secondvanes having alternate chord length and wedge angle;

FIG. 30 shows a channel diffuser having a row of vanes that includefirst and second vanes, the second vanes having an alternate chordlength;

FIG. 31 shows a channel diffuser having a row of vanes that includefirst and second vanes, the second vanes having an alternate chordlength and leading edge location;

FIG. 32 shows a channel diffuser having a row of vanes that includefirst and second vanes, the first vanes having an alternate staggerangle;

FIG. 33 shows a channel diffuser having a row of vanes that includefirst and second vanes, the second vanes having an alternate staggerangle;

FIG. 34 shows a turbomachine having a diffuser and a shroud withflowwise grooves;

FIG. 35 is another view of the diffuser and shroud of FIG. 34;

FIG. 36 is another view of the diffuser and shroud of FIGS. 34 and 35;

FIG. 37 shows a turbomachine having a diffuser and a shroud withflowwise grooves;

FIG. 38 is another view of the diffuser and shroud of FIG. 37;

FIG. 39 is another view of the diffuser and shroud of FIGS. 37 and 38;

FIG. 40 shows a turbomachine having a diffuser and a shroud withflowwise grooves in the hub and shroud;

FIG. 41 is another view of the diffuser and shroud of FIG. 40;

FIG. 42 is another view of the diffuser and shroud of FIGS. 40 and 41;

FIG. 43 shows the hub and shroud of FIGS. 40-42 with the hub clockedrelative to the shroud;

FIG. 44 is an elevation view of the clocked hub and shroud of FIG. 43;

FIG. 45 shows a diffuser having a hub and shroud with flowwise recessesand one set of recesses having a different characteristic than the otherrecesses, resulting in a biased passage;

FIG. 46 is an elevation view of the diffuser of FIG. 45;

FIG. 47 is a cross-sectional view of a diffuser passage, the crosssection taken at a location downstream of a leading edge of the passageand showing recesses in the hub and shroud surfaces of the passage,thereby providing a biased passage;

FIG. 48 shows a turbomachine having a diffuser and a shroud withflowwise channels in the hub and shroud;

FIG. 49 is another view of the diffuser of FIG. 48;

FIG. 50 shows a turbomachine having a diffuser with flowwise channels inthe hub and shroud, one of the channels having a differentcharacteristic than other ones of the channels, resulting in a biasedpassage;

FIG. 51 is an elevation view of the diffuser of FIG. 50;

FIG. 52 shows a vaned diffuser having flowwise channels in a shroudsurface, one of the channels being a biased passage; and

FIG. 53 is an elevation view of the diffuser of FIG. 52.

DETAILED DESCRIPTION

Aspects of the present disclosure include turbomachines having one ormore flow guiding features designed to increase the performance of theturbomachine. In some examples, flow guiding features are designed andconfigured to bias a circumferential pressure distribution at a diffuserinlet toward circumferential uniformity, or otherwise account for suchlow-frequency spatial pressure variations. In some examples, a diffuserhaving a row of vanes that include a plurality of first vanes and atleast one second vane having a different characteristic than the firstvanes are disclosed. In some examples, diffusers having an aperiodicsection including one or more biased passages for biasing a flow fieldare disclosed. In some examples, turbomachines having flowwise elongaterecesses in one or both of a hub and shroud surface are disclosed. Asdescribed herein, the present disclosure includes various combinationsof flow guiding features that may be incorporated in a turbomachine toaccount for flow field characteristics, including but not limited tocircumferential asymmetries, to thereby improve the performance of theturbomachine.

FIGS. 1-5 are graphs of static pressure versus circumferential angle forvarious diffuser types and operating conditions, each of the diffusersoperably arranged downstream of a centrifugal compressor. Each of FIGS.1-5 shows time-averaged static pressure at several circumferentiallocations around the machines, all at a streamwise location betweenimpeller exit and diffuser inlet. FIG. 1 shows time averaged staticpressures for various flowrates 102-116, with curve 104 being the lowestflow rate and 102 the highest, all at the same impeller rotationalspeed, here 120,000 RPM. The data in FIG. 1 is from a flat platediffuser having 14 vanes. Vane location lines 118 show the approximatelocation of each of the vanes with respect to the static pressuremeasurements. As shown in FIG. 1, each of pressure curves 102-116 has asawtooth pattern, with peaks corresponding to each vane location 118,such sawtooth pattern being mostly due to the natural vane-to-vanepressure field that exists in vaned diffusers or any cascade ofturbomachinery vanes. Thus, the pressure curves 102-116 have a firstspatial frequency that is substantially the same as the spatialfrequency of the vanes of the flat plate diffuser. Pressure curves102-116, however, also have a lower-frequency wave type variationsuperposed on the sawtooth shape, the lower-frequency wave having aprimary spatial frequency that is less than the spatial frequency of thevanes. FIG. 2 shows a subset of the pressure curves from FIG. 1—curves102, 104, and 112. FIG. 2 also includes mean pressure curves 202, 204,and 206, which, in this example, are 6^(th) order polynomial curves. Thelow-frequency spatial variation in time-averaged circumferential staticpressure can be seen in the mean pressure curves 202, 204, and 206, inthis example, each flow rate resulting in a low-frequency pressurevariation with two maxima and two minima around the circumference of themachine.

FIGS. 1 and 2 indicate that, contrary to the common assumption made inturbomachinery design that the time averaged circumferential flow andpressure distribution at the diffuser inlet is substantiallyaxisymmetric, the static pressure in fact varies around thecircumference of the machine. In regions where the pressure is high, thevelocities may be generally low and vane incidence may be closer to oneextreme, e.g., low or high, depending, for example, on phase angle. Andin regions where the pressure is low, the velocities may be generallyhigh and vane incidence may be closer to the other extreme, e.g., highor low. Consequently, in regions where the incidence at the diffuserinlet due to this distortion is high, early stall may be more likely andlosses may be relatively high. The flow field in these cases may bedeveloping high flow and low flow regions with different pressures inorder to pass the asymmetric impeller flow into a fixed number ofdiffuser passages.

FIG. 3 shows static pressure test data at three flow rates 302, 304, 306with the same flat plate diffuser as FIGS. 1 and 2, but with thecompressor operating at a different speed, here 135,000 RPM, with curve304 being the lowest flow rate and 302 the highest. Mean pressure curves308, 310, and 312 show a similar low-frequency variation as shown inFIG. 2, and also shows a circumferential shift in local maxima andminima as flow rates decrease and the system approaches surge.

FIGS. 4 and 5 similarly show a time-averaged circumferentialdistribution of static pressure at diffuser inlet for adouble-divergence channel diffuser operably coupled to a centrifugalcompressor impeller operating at 100,000 RPM (FIG. 4) and 135,000 RPM(FIG. 5). In FIG. 4, pressure curves 402 and 404 and mean pressurecurves 408, 410 show a low-frequency circumferential variation having aprimary spatial frequency distribution that is less than the spatialfrequency distribution of the diffuser channels, as indicated by vanelocations 406. Unlike FIGS. 1-3, pressure curves 402 and 404 do not havethe same number of higher-frequency local maxima in the sawtooth patternas the number of vanes at locations 406. Instead, a pocket 412 exists inthe data, which shifts with flow rate. Pocket 412 suggests an offset orrelief process may be occurring to allow the non-uniform flow to enterthe fixed diffuser passages, and indicates potential underperformingdiffuser passages, at least in the region of pocket 412. FIG. 5 includespressure curves 502, 504, 506, and 508 and mean pressure curves 512,514, 516, and 518 corresponding to four different flow rates, all at135,000 RPM. As in FIG. 4, pockets 510 appear at each flowrate.

Extensive testing and analysis of circumferential pressure data forvarious diffuser types have shown that the low-frequency circumferentialpressure distribution shown in FIGS. 1-5 do not originate from anasymmetric flow path located upstream or downstream of the diffuser.FIG. 6 shows an example of an asymmetric flow path in the form of avolute 600 located downstream of diffuser 602. It is well known thatvolutes such as volute 600 create an asymmetry in the flow field of adiffuser, such as diffuser 602, proximate cutwater 604, (also referredto as a volute tongue 604) e.g., creating a volute distortion zone 606extending between locations A and B. In the illustrated example, volutedistortion zone extends from approximately 90 degrees upstream ofcutwater 604 (location “A”) to approximately 45 degrees downstream ofthe cutwater (location “B”). FIG. 7 shows circumferential pressureversus flow rate for a compressor or pump having a volute. As shown inFIG. 7, the volute creates strong circumferential distortions inimpeller exit pressures at low flows due to strong diffusion in thevolute at that condition, which diminishes as flow rate increases andthe volute flow state switches from diffusion to acceleration. Pressurecurves 1 and 2 in FIG. 7 are in volute distortion zone 606 (FIG. 6).

Various diffuser designs have been developed to improve diffuserperformance in machines with asymmetric flow paths such as volutes thattry to account for the large circumferential distortions caused by thevolute or other asymmetric flow path. Other examples of such asymmetricflow paths located upstream or downstream of the diffuser include a sideinlet in front of the impeller, an asymmetric collector, etc. Ratherthan localized bulk pressure distortions caused by an asymmetric flowpath such as a volute, the low frequency pressure variations shown inFIGS. 1-5 extend around the entire circumference of the machine, are anactive phenomena that shift in location with operating condition, andexist whether or not asymmetric flow paths are present. The presentpaper discloses a variety of diffusers having biased passages designedand configured to improve diffuser performance in light of theselow-frequency spatial pressure variations. In some embodiments, biasedpassages are provided that are located, configured, and dimensioned tobias a low-frequency circumferential pressure distribution at a diffuserinlet, such as the low-frequency variations shown in FIGS. 1-5, towardcircumferential uniformity. In other examples, biased passages aredesigned and configured to also, or alternatively, improve theperformance of a turbomachine, including increasing the controllabilityof spatial flow field variations, modifying flow field variations, andimproving the performance of the turbomachinery in light of flow fieldvariations.

The present paper includes a variety of diffuser design variables orcharacteristics that may be combined in any number of differentcombinations to develop a diffuser with biased passages tailored forparticular performance and flow fields. Non-limiting examples of suchdiffuser design variables or characteristics include, but are notlimited to, vane leading edge location, vane trailing edge location, aradial distance of a vane from a diffuser centerline, vane chord length,a maximum thickness of a vane, a vane height, a vane flowwise shapedistribution, a vane stagger angle, vane wedge angle, channel divergenceangle, vane pitch, vane lean, vane twist, vane leading edge shape, e.g.,leading edge chevron, swallowtail or scallop, etc., fixed or moveablevanes, a passage height between hub and shroud surfaces, acircumferential location of a biased passage, a number of biasedpassages, and one or more flowwise channels located in one or both ofhub and shroud surfaces extending upstream and/or downstream of adiffuser passage. One or more diffuser design variables may be adjustedfor a subset of vanes in a diffuser vane row to create one or morebiased passages having a cross-sectional flow area distribution in aflowwise direction that is different than a cross-sectional flow areadistribution of a plurality of other diffuser passages in the same vanerow. Such diffuser design variable combinations may be applied to anytype of diffuser, including, for example, any type of vaned diffuser,including flat plate, airfoil, straight channel, conical, single row ortandem, single or multiple vane type per row, and any solidity, and mayalso be applied to vaneless diffusers.

In yet other examples, diffusers made in accordance with the presentdisclosure include multi-vane groupings, wherein each vane groupingincludes two or more vanes each having one or more differentcharacteristics than other ones of the vanes in the grouping. Thegroupings may be arranged in a periodic arrangement around thecircumference of the machine, or may be arranged in an aperiodicarrangement, thereby resulting in one or more biased passages. The oneor more characteristics that may vary among vanes in a vane grouping mayinclude, but are not limited to, vane leading edge location, vanetrailing edge location, a radial distance of a vane from a diffusercenterline, vane chord length, a maximum thickness of a vane, a vaneheight, a vane flowwise shape distribution, a vane stagger angle, vanewedge angle, channel divergence angle, vane pitch, vane lean, vanetwist, vane leading edge shape, e.g., leading edge chevron, swallowtailor scallop, etc., fixed or moveable vanes, and a passage height betweenhub and shroud surfaces. One or more of such characteristics may bevaried. Such groupings may be designed, configured, and located toimprove the performance of a turbomachine, including increasing thecontrollability of spatial flow field variations, modifying flow fieldvariations, and improving the performance of the turbomachinery in lightof flow field variations, such as the circumferential pressurevariations discussed above.

Examples of vaneless diffusers with biased passages include vanelessdiffusers with flowwise recesses, e.g., channels, grooves, or otherrecesses located in the hub or shroud surface for varying a passageheight in one or more circumferential locations. As described morebelow, elongate recesses include, but are not limited to, flowwisechannels having substantially square edges and flowwise grooves havingrounded edges. In some examples, vaneless diffusers may have anaperiodic arrangement of flowwise recesses. The flowwise length of suchrecesses may vary, from longer recesses extending upstream of thediffuser into the impeller and downstream of the diffuser, to shorterrecesses located at any flowwise location in the diffuser and of anyshorter length. Biased passages disclosed herein may have across-sectional area that is greater than a cross-sectional area ofother passages in a diffuser row. Such increased flow area passage(s)may provide a biased relief passage that may be designed and configuredto accept an asymmetric portion of an impeller exit flow and cause amore uniform distribution of flow into other non-biased passages. Inother examples, biased passages disclosed herein may have a reducedcross-sectional area as compared to the cross-sectional area of othernon-biased passages, including fully blocked passages. Thus, as usedherein, a reduced area biased passage includes fully blocked passages,or the absence of a diffuser passage in a location where a passage wouldbe for a fully periodic diffuser passage arrangement. Such decreasedflow area biased passages may be designed and configured to redistributeor otherwise influence an asymmetric impeller exit flow field, therebyproviding a more uniform distribution of flow in the non-biasedpassages.

The present disclosure also includes experimental and computationalmethods of designing flow structures for turbomachines to improveperformance. In one example, a computational model of a turbomachineand/or diffuser may be developed. A circumferential pressuredistribution may be calculated at one or more operating conditions andthe performance of the diffuser may be analyzed. In some cases, alow-frequency circumferential variation in pressure will be calculatedat the diffuser inlet. The computational model of the diffuser may beiteratively adjusted with the addition of one or more biased passages,and a circumferential pressure distribution and diffuser performance maybe calculated for each case to identify an optimized biased passagedesign. In other examples, rather than calculating a circumferentialpressure distribution, a seeded perturbation in the diffuser inletpressure or other equivalent approach may be applied to thecomputational model for various diffuser designs to determine anoptimized biased passage arrangement. In yet other examples,experimental methods of determining biased passage designs may beimplemented, including instrumenting a testing platform with sufficientpressure measurements around the circumference of a diffuser inlet tofully characterize the primary components of any circumferentialpressure variation. The circumferential pressure variation for variousdiffuser designs with and without biased passages may be measured andimproved biased passage designs determined.

FIGS. 8-20 illustrate exemplary embodiments of vaned diffusers havingone or more biased passages. FIG. 8 shows a portion of an exemplaryvaned flat plate low solidity diffuser 800 that has a row of vanes 802extending between a hub 804 and shroud 806 and extending in a flowwisedirection between a diffuser inlet 808 and exit 810. Row 802 includes aplurality of first vanes 812 and at least one second vane 814. Althoughonly three are shown, first vanes 812 are equally spaced around one ormore portions of diffuser 800. As shown, second vane 814 has a differentcharacteristic than first vanes 812, here a different height, withsecond vane 814 being a partial height vane affixed to hub 804. Thepartial height of second vane 814 results in a biased passage 816 thathas a different cross-sectional area distribution in the flowwisedirection than passage 816 between first vanes 812. Thus, diffuser 800has a plurality of passages located around a circumference of thediffuser, including at least one periodic section of passages 816extending between first vanes 812, wherein the section is periodicbecause the first vanes 812 are equally spaced at regular intervalsaround a diffuser centerline. Diffuser 800 also includes at least oneaperiodic section including biased passage 818, the section beingaperiodic because there is a discontinuity in the periodic nature offirst vanes 812, here, biased passage 818 having a largercross-sectional flow area than passages 816. Exemplary diffuser 800 isdesigned and configured for receiving a flow field having acircumferential pressure distribution and biased passage 816 is located,configured, and dimensioned to bias the circumferential pressuredistribution toward circumferential uniformity, e.g., bias alow-frequency spatial pressure variation, such as the ones shown inFIGS. 1-5. Biased passage may also be located, configured, anddimensioned to improve the performance of a turbomachine, includingincreasing the controllability of spatial flow field variations,modifying flow field variations, and improving the performance of theturbomachinery in light of flow field variations. Diffuser 800 may haveone or more of biased passages 816 located at any location around thecircumference of the diffuser. FIG. 9 shows a diffuser 900 that issubstantially the same as diffuser 800, including first vanes 902extending between hub 904 and shroud 906, and at least one second vane908, wherein second vane is partial height and results in biasedpassage. Unlike diffuser 800, second vane 908 is affixed to the shroud906, rather than hub 904. Alternative embodiments may includecombinations of second vanes 814 and 908, e.g., a single diffuser withone or more partial-height vanes affixed to the shroud surface and oneor more partial-height vanes affixed to the hub surface.

FIG. 10 shows an exemplary diffuser 1000 that has a plurality of firstvanes 1002 and at least one second vane 1004 having a differentcharacteristic, here radial distance from a centerline 1005 of diffuser1000 and stagger angle, thereby forming biased passage 1006. Broken line1008 shows where one of first vanes 1002 would have been located if theperiodic nature of first vanes had been continued, e.g., a periodicfirst vane location, as is the case with existing diffusers. Brokenlines 1010 illustrate the stagger angle may be varied +/−from a firstvane stagger angle. Although only a portion of diffuser 1000 is shown,the diffuser may include one or more biased passages 1006. First andsecond vanes 1002, 1004 may all be full height, or one or both may bepartial height. As shown, exemplary second vane 1004 is slid back alonga flowwise direction as compared to periodic first vane location 1008,resulting in leading edge 1012 and trailing edge 1014 both being agreater radial distance from centerline 1005 than leading and trailingedges 1016, 1018 of first vanes 1002. Biased passage 1006 creates anaperiodic section in diffuser 1000 in the form of a largercross-sectional flow area at inlet 1020 of diffuser 1000.

FIG. 11 shows an exemplary diffuser 1100 that has a plurality of firstvanes 1102 and at least one second vane 1104 having a differentcharacteristic, here thickness, thereby forming biased passages 1106.Although only a portion of diffuser 1100 is shown, the diffuser mayinclude two or more biased passages 1106. First and second vanes 1102,1104 may all be full height, or one or both may be partial height. Asshown, exemplary second vane 1104 is thinner than first vanes 1102,resulting in biased passages 1106 that have a different cross-sectionalarea distribution than passages 1108, creating an aperiodic section indiffuser 1100 in the form of a larger cross-sectional flow area adjacentsecond vane 1104.

FIG. 12 shows an exemplary diffuser 1200, which is similar to diffuser1100 (FIG. 11) and has a plurality of first vanes 1202 and at least onesecond vane 1204 having a different characteristic, here maximumthickness, thereby forming biased passages 1206. Although only a portionof diffuser 1200 is shown, the diffuser may include two or more biasedpassages 1206. First and second vanes 1202, 1204 may all be full height,or one or both may be partial height. As shown, exemplary second vane1204 is thicker than first vanes 1202, resulting in biased passages 1206that have a different cross-sectional area distribution than passages1208, creating an aperiodic section in diffuser 1200 in the form of asmaller cross-sectional flow area adjacent second vane 1204.

FIG. 13 shows an exemplary diffuser 1300, which is similar to diffusers1100 and 1200 (FIGS. 11 and 12) and has a plurality of first vanes 1302and at least one second vane 1304 having a different characteristic,here chord length, thereby forming biased passages 1306. Although only aportion of diffuser 1300 is shown, the diffuser may include two or morebiased passages 1306. First and second vanes 1302, 1304 may all be fullheight, or one or both may be partial height. As shown, exemplary secondvane 1304 is longer than first vanes 1302, resulting in biased passages1306 that have a different flowwise cross-sectional area distributionthan passages 1308, creating an aperiodic section in diffuser 1300proximate second vane 1304. FIG. 14 shows diffuser 1400, which issubstantially the same as diffuser 1300 with equivalent componentshaving the same name and same reference numeral suffix. Unlike diffuser1300, second vane 1404 may have a different stagger angle than firstvanes 1402, as indicated by broken line 1410, showing one possiblealternative stagger angle. The particular stagger angle of second vane1404 may be varied, including both positive and negative angles withrespect to the first vane 1402 stagger angle.

FIG. 15 shows an exemplary diffuser 1500, which is similar to diffusers1100-1400 (FIGS. 11-14) and has a plurality of first vanes 1502 and atleast one second vane 1504 having a different characteristic, herepitch, resulting in a different circumferential spacing between secondvane 1504 and adjacent vanes than the spacing between adjacent firstvanes 1502, thereby forming biased passages 1506 a and 1506 b. Biasedpassage 1506 a has a smaller cross-sectional area and 1506 b has alarger cross-sectional area than passages 1508. Although only a portionof diffuser 1500 is shown, the diffuser may include two or more biasedpassages 1506 a, b. First and second vanes 1502, 1504 may all be fullheight, or one or both may be partial height. As shown, exemplary secondvane 1504 has the same pitch, shape, and chord length as first vanes1202, but is located at a different circumferential location than aperiodic first vane location, resulting in an aperiodic section anddiffuser 1500 having a non-uniform and aperiodic circumferential vanepitch distribution.

FIG. 16 shows exemplary diffuser 1600, which has a plurality of firstvanes 1602 (only two of twelve labeled) and two second vanes 1604 a,1604 b each having a different characteristic, here maximum thicknessand chord length, than the first vanes, resulting in biased passages1606 a and 1606 b. Second vane 1604 a has the same thickness as thefirst vanes 1602, but a longer chord length, resulting in biasedpassages 1606 a having a different flowwise cross-sectional areadistribution than passages 1608. Second vane 1604 b has a greaterthickness than first vanes 1602, resulting in biased passages 1606 bhaving a different flowwise cross-sectional area distribution, includinga smaller cross-sectional area, than passages 1608. First and secondvanes 1602, 1604 a, 1604 b may all be full height, or one or more may bepartial height. As shown, second vanes 1604 a, 1604 b and associatedbiased passages 1606 a, 1606 b are spaced approximately 180 degreesaround the circumference of diffuser 1600. First vanes 1602 are equallyspaced from adjacent first vanes, providing two periodic sections 1610and second vanes 1604 a, 1604 b result in two aperiodic sections 1612.

FIG. 17 shows exemplary diffuser 1700, which has a plurality of firstvanes 1702 (only two of seven labeled) and a plurality of second vanes1704 (only two of seven labeled), each having a different characteristicfrom first vanes 1702, here chord length. Unlike diffuser 1600, diffuser1700 has an equal number of first vanes 1702 and second vanes 1704 and afully periodic arrangement of passages 1706 a, 1706 b. First vanes 1702and second vanes 1704 may all be full height, or one or more may bepartial height. First and second vanes 1702, 1704 are arranged in vanegroupings, here two vanes per grouping, where diffuser 1700 has aperiodic arrangement of multi-vane groupings, and wherein each vanegrouping includes first and second vanes 1702, 1704, each having adifferent characteristic than other ones of the vanes in the grouping.FIG. 18 shows diffuser 1800, which is substantially the same as diffuser1700, including a plurality of first vanes 1802 (only two of sevenlabeled) and a plurality of second vanes 1804 (only two of sevenlabeled), each having a different characteristic from first vanes 1802,here chord length. Unlike diffuser 1700, each of second vanes 1804 alsohave a different flowwise location than first vanes 1802, with alocation of leading edge 1812 being at a different radial distance, herea greater distance, from diffuser centerline 1814, than a radialdistance of first vane leading edges 1816 from the diffuser centerline.For example, each of second vanes 1804 are slid back in a flowwisedirection as compared to a periodic first vane location. As withdiffuser 1700, diffuser 1800 includes first and second vanes 1802, 1804that are arranged in multi-vane groupings, here two vanes per grouping,where diffuser 1800 has a periodic arrangement of multi-vane groupings.In other examples, one or more characteristics of one or more of firstand/or second vanes 1702, 1802, 1704, 1804 may be varied to create oneor more aperiodic sections having biased passages that are configured toaddress asymmetric pressure fields, for example, the asymmetric pressurefields shown in FIGS. 1-5. The one or more characteristics may include,for example, any of the characteristics described herein, such as vaneheight, stagger angle, pitch, vane shape, vane leading and trailing edgelocation, and chord length, etc.

FIG. 19 shows exemplary diffuser 1900, which has a plurality of firstvanes 1902 (only two of seven labeled) and a plurality of second vanes1904 (only two of seven labeled), each having a different characteristicfrom first vanes 1902, here chord length and stagger angle. Diffuser1900 has an equal number of first vanes 1902 and second vanes 1904 andwhen second vanes 1904 are all at the same stagger angle, a fullyperiodic arrangement of passages 1906 a, 1906 b. First vanes 1902 andsecond vanes 1904 may all be full height, or one or more may be partialheight. First and second vanes 1902, 1904 are arranged in vanegroupings, here two vanes per grouping, where diffuser 1900 has aperiodic arrangement of multi-vane groupings. As indicated by brokenlines 1910, the stagger angle of second vanes 1904 may be the same asfirst vanes 1902, or may be varied in a positive or negative directionfrom the first vane stagger angle. In some embodiments, the staggerangle of the second vanes 1904 may be varied, and may be arranged toform an aperiodic arrangement with one or more biased passages. Forexample, all but one of the second vanes 1904 may have the same staggerangle as first vanes 1902, with one of the second vanes having analternate stagger angle, thereby providing two biased passages on eitherside of the altered-angle full height second vane. In other examples,the stagger angle of other numbers of second vanes 1904 may be varied.

FIG. 20 shows exemplary diffuser 2000, which is substantially the sameas diffuser 1900 with equivalent components having the same name andsame reference numeral suffix. Unlike diffuser 1900, where the staggerangle of second vanes 1904 may be varied, in diffuser 2000, the staggerangle of first vanes 2002 may be varied, as indicated by broken lines2010. As with diffuser 1900, the stagger angle of less than all of firstvanes 2002 may be different than other ones of the first vanes, therebyresulting in an aperiodic arrangement and one or more biased passages.First and second vanes 2002, 2004 are arranged in vane groupings, heretwo vanes per grouping, where diffuser 2000 has a periodic arrangementof multi-vane groupings. In other examples, characteristics of diffusers1900 and 2000 may be combined, including varying the stagger angle ofselect ones of both the first and second vanes, or the stagger angle ofa subset of first vanes 1902, 2002, or a subset of second vanes 1904,2004.

In another embodiment, an exemplary diffuser may include a plurality ofvane groupings, wherein each vane in the grouping has a differentheight. For example, a vane grouping may include two partial-heightvanes, including a first partial height vane affixed to a hub or shroudsurface and a second, adjacent partial height vane affixed to the hub orshroud surface. The diffuser may include a periodic arrangement of suchgroupings, e.g., in one example the first and second partial heightvanes may all be equally spaced around the circumference of the machine.In one example, the first partial height vane may have a differentheight than the second partial height vane. For example, the firstpartial height vane may have a height between approximately 15% andapproximately 65% of a passage height, and in some examples,approximately 50% of the passage height. The second partial height vanemay have a height between approximately 5% and approximately 45% of thepassage height, and in some examples, approximately 15%. In one example,the first and second partial height vanes in each vane grouping may beaffixed to opposite sides of the passage, e.g., the first partial heightvane may be affixed to the shroud and the second partial height vane maybe affixed to the hub. Such partial-height vane groupings may reduceleading edge metal blockage and increase passage area, and allow forflow reorganization especially near choke, thereby improvingperformance. In yet other examples, vane groupings may include three ormore vanes, such vane groupings repeated around the perimeter of thediffuser. In yet other examples, one or more biased passages may beformed by locating such vane groupings adjacent periodic sections. Forexample, in a diffuser with 14 vanes, a two vane grouping with first andsecond partial height vanes may be used in the place of 2 to 12 of the14 vanes in one or more circumferential locations resulting in one ormore biased passages.

FIG. 21 shows a prior art channel-type diffuser 2100 and FIGS. 22-33show exemplary embodiments of channel-type diffusers made in accordancewith the present disclosure. As shown in FIG. 21, prior art channel-typediffuser 2100 includes a plurality of vanes 2102 (only one labeled)defining passages 2104 (only one labeled) in the form of channels.Diffuser 2100 is similar to the diffuser used to generate the test datashown in FIGS. 4 and 5. Diffuser 2100 is fully periodic and symmetric,with each of vanes 2102 having the same stagger angle S and wedge angleW, and each passage 2104 having the same divergence angle D.

FIG. 22 shows an exemplary channel diffuser 2200 having a plurality ofpassages 2202 (only one labeled) extending between a first vane 2204(only one labeled). Unlike prior art diffuser 2100, however, eachpassage 2202 also includes a second vane 2206 located between adjacentfirst vanes 2204. Exemplary second vanes 2206 are flat plates, each havea leading edge 2208 that is downstream from diffuser inlet 2210, and atrailing edge 2212 that is positioned upstream of diffuser exit 2214.Second vanes 2206 are full height. In other examples, one or more offirst and/or second vanes 2204, 2206 may be partial height. In theillustrated example, second vanes 2206 have a shorter chord length thana length of passages 2202, and are substantially centered in thepassages in both circumferential and flowwise directions. First andsecond vanes 2204, 2206 are arranged in vane groupings, here two vanesper grouping, where diffuser 2200 has a periodic arrangement ofmulti-vane groupings. Exemplary passages 2202 are periodic, however, oneor more characteristics of one or more of first vanes 2204 and/or secondvanes 2206 may be varied to create one or more biased passages. One ormore characteristics of one or more of first and/or second vanes 2204,2206 may be varied to create one or more aperiodic sections havingbiased passages that are configured to address asymmetric pressurefields, for example, the asymmetric pressure fields shown in FIGS. 1-5.The one or more characteristics may include, for example, any of thecharacteristics described herein, such as vane height, stagger angle,pitch, vane shape, vane leading and trailing edge location, and chordlength, etc. For example, second vanes 2206 may be of any type includingairfoil type and need not all be centered in passages 2202; at least onemay be relocated or resized to create a biased passage including partialheight design.

FIG. 23 shows an exemplary channel diffuser 2300, which is similar tochannel diffuser 2200 with equivalent components having the same nameand same reference numeral suffix. Diffuser 2300 includes a plurality ofpassages 2302 (only one labeled) extending between first vanes 2304(only one labeled). Each passage 2302 also includes a second vane 2306located between adjacent first vanes 2304. Exemplary second vanes 2306are flat plates. As compared to second vanes 2206 (FIG. 22), secondvanes 2306 are narrower and positioned farther upstream, in this examplewith leading edge 2308 located at diffuser inlet 2310, and trailing edge2312 located farther upstream of diffuser exit 2314. Second vanes 2306are full height. In other examples, one or more of first and/or secondvanes 2304, 2306 may be partial height. In the illustrated example,second vanes 2306 have a shorter chord length than a length of passages2302, and are substantially centered in the passages in acircumferential direction and located upstream of a passage 2302midpoint in the flowwise direction. First and second vanes 2304, 2306are arranged in vane groupings, here two vanes per grouping, wherediffuser 2300 has a periodic arrangement of multi-vane groupings.Exemplary passages 2302 are periodic, however, one or morecharacteristics of one or more of first vane 2304 and/or second vanes2306 may be varied to create one or more biased passages. One or morecharacteristics of one or more of first and/or second vanes 2304, 2306may be varied to create one or more aperiodic sections having biasedpassages that are configured to address asymmetric pressure fields, forexample, the asymmetric pressure fields shown in FIGS. 1-5. The one ormore characteristics may include, for example, any of thecharacteristics described herein, such as vane height, stagger angle,pitch, vane shape, vane leading and trailing edge location, and chordlength, etc. For example, second vanes 2306 may be of any type includingairfoil type and need not all be centered in passages 2302; at least onemay be relocated or resized to create a biased passage including partialheight design.

FIG. 24 shows an exemplary channel diffuser 2400 that is the same asprior art diffuser 2100 (FIG. 21) except that diffuser 2400 includes aplurality of first vanes 2402 and one second vane 2404 that has acharacteristic that is different than first vanes 2402, here, wedgeangle. In the illustrated example, diffuser 2400 includes a singlesecond vane 2404 located in a first vane 2402 periodic location, orwhere a first vane 2402 would have been located in a prior artarrangement. Second vane 2404 has a lower wedge angle W2 than first vane2402 wedge angle W1. The smaller wedge angle W2 of second vane 2404results in two biased passages 2406. Diffuser 2400 includes a periodicsection 2408 of first vanes 2402 and associated passages 2410 and anaperiodic section 2412 including the two biased passages 2406. In otherexamples, one or more additional first vanes 2402 may be replaced withsecond vanes 2404 that may have one or more characteristics that aredifferent than first vanes 2402, thereby creating one or more additionalbiased passages.

FIG. 25 shows an exemplary channel diffuser 2500 that is similar todiffuser 2400 (FIG. 24) with equivalent components having the same nameand same reference numeral suffix. Diffuser 2500 includes a plurality offirst vanes 2502 and one second vane 2504 that has a characteristic thatis different than first vanes 2502, here, wedge angle. Unlike diffuser2400, second vane 2504 has a larger wedge angle than first vanes 2502.In the illustrated example, diffuser 2500 includes a single second vane2504 located in a first vane 2502 periodic location, or where a firstvane 2502 would have been located in a prior art arrangement. Secondvane 2504 has a larger wedge angle W2 than first vane 2502 wedge angleW1. The larger wedge angle W2 of second vane 2404 results in two biasedpassages 2506 that have a smaller cross-sectional area than passages2510. Diffuser 2500 includes a periodic section 2508 of first vanes 2502and associated passages 2510 and an aperiodic section 2512 including thetwo biased passages 2506. In other examples, one or more additionalfirst vanes 2502 may be replaced with second vanes 2504 that may haveone or more characteristics that are different than first vane 2502,thereby creating one or more additional biased passages.

FIG. 26 shows an exemplary channel diffuser 2600 that is similar todiffusers 2400 (FIG. 24) and 2500 (FIG. 25) with equivalent componentshaving the same name and same reference numeral suffix. Diffuser 2600includes a plurality of first vanes 2602 and one second vane 2604 thathas a characteristic that is different than first vane 2602, here, chordlength. In the illustrated example, diffuser 2600 includes a singlesecond vane 2604 located in a first vane 2602 periodic location, orwhere a first vane 2602 would have been located in a prior artarrangement. The longer length of second vane 2604 results in two biasedpassages 2606 that have a different flowwise cross-sectional areadistribution than passages 2610, and result in the trailing edge ofsecond vane 2604 acting as an additional flow guide at diffuser exit toreduce losses at the diffuser exit. Diffuser 2600 includes a periodicsection 2608 of first vanes 2602 and associated passages 2610 and anaperiodic section 2612 including the two biased passages 2606. In otherexamples, one or more additional first vanes 2602 may be replaced withsecond vanes 2604 that may have one or more characteristics that aredifferent than first vanes 2602, thereby creating one or more additionalbiased passages.

FIG. 27 shows an exemplary channel diffuser 2700 that is similar todiffusers 2400 (FIG. 24), 2500 (FIG. 25), and 2600 (FIG. 26) withequivalent components having the same name and same reference numeralsuffix. Diffuser 2700 includes a plurality of first vanes 2702 and onesecond vane 2704 that has a characteristic that is different than firstvane 2702, here, vane stagger angle, resulting in alternate passagedivergence angles. In the illustrated example, diffuser 2700 includes asingle second vane 2704 located approximately where a first vane 2702would have been located in a prior art arrangement. As indicated by thebroken lines, the stagger angle of second vane 2704 may be varied in a+/−direction relative to the stagger angle of first vanes 2702,resulting in two biased passages 2706 that have a different flowwisecross-sectional area distribution than passages 2710. Diffuser 2700includes a periodic section 2708 of first vanes 2702 and associatedpassages 2710 and an aperiodic section 2712 including the two biasedpassages 2706. In other examples, one or more additional first vanes2702 may be replaced with second vanes 2704 that may have one or morecharacteristics that are different than first vanes 2702, therebycreating one or more additional biased passages.

FIG. 28 shows an exemplary channel diffuser 2800 that is similar todiffusers 2400 (FIG. 24), 2500 (FIG. 25), 2600 (FIG. 26), and 2700 (FIG.27) with equivalent components having the same name and same referencenumeral suffix. Diffuser 2800 includes a plurality of first vanes 2802and one second vane 2804 that has a characteristic that is differentthan first vane 2802, here, vane pitch, thereby altering vanecircumferential location and spacing. In the illustrated example,diffuser 2800 includes a single second vane 2804 in the place of one offirst vane 2802. As shown, the pitch of second vane 2804 is differentthan the pitch of first vanes 2802, resulting in two biased passages2806 a, 2806 b that have different flowwise cross-sectional areadistributions than passages 2810. Diffuser 2800 includes a periodicsection 2808 of first vanes 2802 and associated passages 2810 and anaperiodic section 2812 including the two biased passages 2806 a, 2806 b.In other examples, one or more additional first vanes 2802 may bereplaced with second vanes 2804 that may have one or morecharacteristics that are different than first vane 2802, therebycreating one or more additional biased passages.

FIG. 29 shows an exemplary diffuser 2900, which combines thecharacteristics of diffusers 2500 (FIG. 25) and 2600 (FIG. 26). Asshown, diffuser 2900 includes a plurality of first vanes 2902 and twosecond vanes 2904 a, 2904 b that each have a characteristic that isdifferent than first vanes 2902. Second vane 2904 a has a greater chordlength than first vanes 2902 and second vane 2904 b has a greater wedgeangle W2 than wedge angle W1 of first vanes 2902, resulting in biasedpassages 2906 a and 2906 b that have different flowwise cross-sectionalarea distributions than passages 2910. Diffuser 2900 includes periodicsections 2908 a, 2908 b of first vanes 2902 and associated passages 2910and aperiodic sections 2912 a, 2912 b including biased passages 2906 a,2906 b, respectively. In other examples, one or more additional firstvanes 2902 may be replaced with second vanes 2904 that may have one ormore characteristics that are different than first vanes 2902, therebycreating one or more additional biased passages.

FIG. 30 shows an exemplary channel diffuser 3000 which has a pluralityof first vanes 3002 (only one labeled) and a plurality of second vanes3004 (only one labeled), each of the second vanes having a differentcharacteristic from first vanes 3002, here chord length. Diffuser 3000has an equal number of first vanes 3002 and second vanes 3004 and afully periodic arrangement of passages 3006 a, 3006 b. As with any ofthe channel diffusers disclosed herein, first vanes 3002 and secondvanes 3004 may all be full height, or one or more may be partial height.FIG. 31 shows diffuser 3100, which is similar to diffuser 3000,including a plurality of first vanes 3102 (only one labeled) and aplurality of second vanes 3104 (only one labeled), each of the secondvanes having a different characteristic from first vanes 3102, herechord length and flowwise location. Each of second vanes 3104 have adifferent flowwise location than first vanes 3102, with a location ofleading edge 3112 being at a different radial distance, here a greaterdistance, from diffuser centerline 3114, than a radial distance of firstvane leading edges 3116 from the diffuser centerline. For example, eachof second vanes 3104 are slid back in a flowwise direction as comparedto a periodic first vane location. One or more characteristics of one ormore of first and/or second vanes 3002, 3102, 3004, 3104 may be variedto create one or more aperiodic sections having biased passages that areconfigured to address asymmetric pressure fields, for example, theasymmetric pressure fields shown in FIGS. 1-5. The one or morecharacteristics may include, for example, any of the characteristicsdescribed herein, such as vane height, stagger angle, pitch, vane shape,vane leading and trailing edge location, and chord length, etc.

FIG. 32 shows an exemplary channel diffuser 3200 which is substantiallythe same as diffuser 3000 (FIG. 30) with equivalent components havingthe same name and same reference numeral suffix. Unlike diffuser 3000,where the wedge angle, vane stagger, and channel divergence angles offirst and second vanes 3002, 3004 are the same, the stagger angle offirst vane 3202 and associated channel diverge angles of adjacentpassages 3206 may be varied in either direction from a stagger angle ofsecond vanes 3204. In some examples, the stagger angle of less than allof first vanes 3202 may be different than other ones of the first vanes,thereby resulting in an aperiodic arrangement and one or more biasedpassages 3206. FIG. 33 shows diffuser 3300, which is substantially thesame as diffuser 3200, except that rather than varying the stagger angleof first vanes 3302, the stagger angle of one or more second vanes 3304and associated channel divergence angles of adjacent passages 3306 maybe varied. In some examples, the stagger angle of less than all ofsecond vanes 3304 may be varied, resulting in diffuser 3300 having oneor more aperiodic sections having one or more biased passages. In otherexamples, any one or more of the vane characteristic variationsillustrated in FIGS. 22-33 may be combined in any combination.

FIG. 34 is an isometric view of a turbomachine 3400, including impeller3402 and vaneless diffuser 3404. Diffuser 3404 extends between shroud3406 and hub 3407. Shroud 3406 extends from an impeller inlet 3408,across an impeller exit/diffuser inlet 3410 to diffuser outlet 3412.FIGS. 35 and 36 are additional views of shroud 3406 and hub 3407. Asshown in FIGS. 35 and 36, exemplary shroud 3406 includes a plurality offlowwise grooves 3502 (only one labeled) that extend in a flowwisedirection from a location upstream of diffuser inlet and adjacentimpeller 3402, to a location downstream of the diffuser inlet, in thisexample to diffuser outlet 3412 (FIG. 34). Flowwise grooves 3502 arelocated in the surface of shroud 3406 and have rounded edges 3504,giving the shroud wall a circumferential profile that approximates aperiodic waveform. Exemplary grooves 3502 may be designed and configuredto guide a portion of fluid flow in impeller 3402 into diffuser 3404 ata preferred angle, thereby increasing the performance of turbomachine3400. FIGS. 37-39 show turbomachine 3700, which is substantially thesame as turbomachine 3400 with equivalent components having the samename and same reference numeral suffix. Unlike turbomachine 3400,turbomachine 3700 has flowwise grooves 3802 that are more closely spacedthan flowwise grooves 3502 (FIG. 35), with edges 3804 of adjacentgrooves 3802 substantially touching at a leading edge region of thegrooves.

FIGS. 40-42 show an exemplary turbomachine 4000, which has the sameimpeller 3402 and shroud 3406 as turbomachine 3400 (FIGS. 34-36), but analternative hub 4002, that, as can be best seen in FIG. 42, also hasflowwise grooves that extend in a flowwise direction, in this example,from diffuser inlet 4204 to diffuser outlet 4206. In the example shown,diffuser 4004 has the same number of grooves 4202 as grooves 3502 inshroud 3406, and similarly has grooves with rounded edges 4208. Grooves4202 are circumferentially aligned with grooves 3502. As with grooves3502, hub-side grooves 4202 may be designed and configured to guide aportion of working fluid in a preferred direction to improve theperformance of diffuser 4004. FIGS. 43 and 44 show an alternateconfiguration from FIGS. 40-42, wherein a circumferential location ofhub-side grooves 4202 are clocked with respect to shroud-side grooves3502. In this example, each of hub-side grooves 4202 are aligned with amidpoint between adjacent shroud-side grooves 3502. In other examples,any other relative circumferential positioning may be used.

FIGS. 45 and 46 show an exemplary shroud 4502 and hub 4504, each havingflowwise grooves 4506 and 4508, respectively. Unlike the embodimentsshown in FIGS. 40-44, shroud 4502 and hub 4504 also include biasedpassages 4510, 4512, in the form of enlarged flowwise grooves that havea larger cross-sectional area than grooves 4506, 4508. Such biasedpassages may be located, configured, and dimensioned to bias acircumferential pressure distribution toward circumferential uniformity,and/or provide other performance enhancements described herein. In otherexamples, one or both of shroud 4502 and hub 4504 may have additionalbiased flowwise grooves, or one or more biased flowwise grooves may belocated in only the shroud or hub. The examples shown in FIGS. 45 and 46include a periodic portion of passageways in the form of flowwisegrooves and an aperiodic portion, in the illustrated example, having onebiased passageway.

FIG. 47 is a cross-sectional elevation view of a biased diffuser passage4702 disposed between passages 4704. Biased passage 4702 has anincreased passage height H1 from recesses 4706 located in shroud 4708and recess 4710 located in shroud 4712. Recesses 4706 and 4710 may besimilar in shape and location to grooves 3502 (FIG. 35), 4202 (FIG. 42),or may have other configurations, e.g., different leading and/ortrailing edge location, width, flowwise length, etc. For example, insome embodiments, recesses 4706 and 4710 may have a leading edge locatedat a diffuser inlet. In the example shown in FIG. 47, only one recess4706, 4710 is located in the hub and shroud 4708, 4712, thereby creatingan aperiodic portion having a biased passage with a largercross-sectional area than other passages in diffuser 4700. In otherexamples a plurality of diffuser passages may have an increased heightfrom one or more recesses located in the hub and/or shroud.

FIG. 48 is an isometric view of a turbomachine 4800, including impeller4802 and vaneless diffuser 4804. Diffuser 4804 extends between shroud4806 and hub 4807. Shroud 4806 extends from an impeller inlet 4808,across an impeller exit/diffuser inlet 4810 to diffuser outlet 4812.FIG. 49 is an additional view of shroud 4806 and hub 4807. As shown inFIGS. 48 and 49, exemplary shroud 4806 and hub 4807 each include aplurality of flowwise channels 4820, 4822, respectively (only one ofeach labeled) that extend in a flowwise direction. Channels 4820, 4822as well as flowwise grooves 3502 (FIG. 35), 3802 (FIG. 38), and 4202(FIG. 42) are all flowwise elongate recesses. Channels 4820 and 4822differ from grooves 3502, 3802, 4202, by the cross-sectional shape ofthe recess, with the channels having a substantially square edge 4902(FIG. 49) and the grooves having a rounded edge 3504 (FIG. 35). Shroudsurface channels 4820 extend from a location upstream of diffuser inlet4810 and adjacent impeller 4802, to a location downstream of thediffuser inlet, in this example to diffuser outlet 4812. Hub surfacechannels 4822 extend across the entire length of hub 4807 from diffuserinlet 4810 to diffuser outlet 4812. Flowwise channels 4820 are locatedin the surface of shroud 4806 and have substantially square edges 4902giving the shroud wall a circumferential profile that approximates aperiodic square waveform. Similarly, flowwise channels 4822 are locatedin the surface of hub 4807 and have substantially square edges 4904giving the hub wall a circumferential profile that approximates aperiodic square waveform. Exemplary channels 4820 and 4822 may bedesigned and configured to guide a portion of fluid flow in impeller4802 into diffuser 4804 at a preferred angle, thereby increasing theperformance of turbomachine 4800. In other embodiments, thecharacteristics of one or both of channels 4820, 4822 may be varied,such as a depth, width, and number of channels. In the example shown inFIGS. 48 and 49, channels 4820 and 4822 are circumferentially aligned,however, in other examples, the relative positions may be clocked suchthat the hub and shroud channels are not aligned.

FIGS. 50 and 51 show an alternative diffuser 5000 that is similar todiffuser 4804 (FIG. 48) and includes hub 5002 and shroud 5004 having hubflowwise channels 5006 and shroud flowwise channels 5008. Unlikediffuser 4804, one of each of channels 5006 and 5008 have acharacteristic that is different than the other channels 5006, 5008,here, a channel 5006 a and 5008 a each having an enlarged depth,resulting in a biased passage. In other examples, a characteristic ofjust hub channels 5006 or just shroud channels 5008 may be varied fromother ones of the hub and shroud channels to create a biased passage. Insome examples, characteristics other than depth may be varied, such ascross-sectional shape (e.g., groove versus channel), width, length,leading edge location, and trailing edge location). In some examples,more than one of hub and/or shroud channels 5006, 5008 may be varied tocreate a larger aperiodic section having more than one biased passage,or more than one aperiodic section. In yet other examples, diffusersmade in accordance with the present disclosure may have a smaller numberof flowwise recesses located at select circumferential locations, ratherthan a plurality of flowwise recesses equally spaced around the entirecircumference of the machine. For example, diffusers made in accordancewith the present disclosure may have only one, two, three, etc. flowwiserecesses located in select locations around the circumference of themachine.

FIGS. 52 and 53 show an exemplary vaned diffuser 5200 having a shroud5202 and hub 5204, the shroud extending from an impeller inlet 5206,across a diffuser inlet 5208 to a diffuser exit 5210. Shroud 5202includes flowwise channels 5212 extending to locations upstream anddownstream of diffuser inlet 5208 and are separated by upper legs 5214of a leading edge 5216 of vanes 5218. In the illustrated example,leading edges 5216 have a scalloped, also referred to herein as aswallowtail shape. In the illustrated example, hub 5204 does not includeany flowwise recesses. In other examples, hub 5204 may include flowwiserecesses, such as channels or grooves.

As shown in FIGS. 52 and 53, a biased channel 5212 a has a differentcharacteristic than the other channels 5212, here, a leading edgelocation 5220 that is farther upstream than a leading edge location 5222of channels 5212 (best seen in FIG. 52) and a depth that is greater thana depth of channels 5212 (best seen in FIG. 53). Biased channel 5212 acreates a biased passage in a aperiodic section of diffuser 5200.

The foregoing has been a detailed description of illustrativeembodiments of the invention. It is noted that in the presentspecification and claims appended hereto, conjunctive language such asis used in the phrases “at least one of X, Y and Z” and “one or more ofX, Y, and Z,” unless specifically stated or indicated otherwise, shallbe taken to mean that each item in the conjunctive list can be presentin any number exclusive of every other item in the list or in any numberin combination with any or all other item(s) in the conjunctive list,each of which may also be present in any number. Applying this generalrule, the conjunctive phrases in the foregoing examples in which theconjunctive list consists of X, Y, and Z shall each encompass: one ormore of X; one or more of Y; one or more of Z; one or more of X and oneor more of Y; one or more of Y and one or more of Z; one or more of Xand one or more of Z; and one or more of X, one or more of Y and one ormore of Z.

Various modifications and additions can be made without departing fromthe spirit and scope of this invention. Features of each of the variousembodiments described above may be combined with features of otherdescribed embodiments as appropriate in order to provide a multiplicityof feature combinations in associated new embodiments. Furthermore,while the foregoing describes a number of separate embodiments, what hasbeen described herein is merely illustrative of the application of theprinciples of the present invention. Additionally, although particularmethods herein may be illustrated and/or described as being performed ina specific order, the ordering is highly variable within ordinary skillto achieve aspects of the present disclosure. Accordingly, thisdescription is meant to be taken only by way of example, and not tootherwise limit the scope of this invention.

Exemplary embodiments have been disclosed above and illustrated in theaccompanying drawings. It will be understood by those skilled in the artthat various changes, omissions and additions may be made to that whichis specifically disclosed herein without departing from the spirit andscope of the present invention.

What is claimed is:
 1. A diffuser, comprising: an inlet, a hub, and ashroud; and a row of vanes including a plurality of vane groupings eachincluding a first partial height vane affixed to the hub and a secondpartial height vane circumferentially spaced from the first partialheight vane and affixed to the shroud; wherein each of the first andsecond partial height vanes have a leading edge, the leading edges ofthe first and second partial height vanes being substantially aligned ina flowwise direction; wherein a height of the first partial height vanesis different than a height of the second partial height vanes; whereinthe height of at least one of the first partial height vanes or at leastone of the second partial height vanes is greater than 50% of a passageheight at the diffuser inlet.
 2. The diffuser according to claim 1,wherein the diffuser has a circumference, the plurality of vanegroupings located around the circumference of the diffuser and formingat least one periodic section of the vane groupings.
 3. The diffuseraccording to claim 2, further comprising at least one aperiodic section,the at least one aperiodic section including at least one biased passagedefined by at least one vane having a different characteristic than thefirst and second partial height vanes.
 4. The diffuser according toclaim 3, wherein the different characteristic of the at least one vanedefining the at least one biased passage includes one or more of leadingedge location, trailing edge location, chord length, maximum thickness,height, flowwise shape distribution, stagger angle, pitch, wedge angle,lean, twist, and leading edge shape.
 5. The diffuser according to claim1, wherein the plurality of vane groupings define a plurality ofdiffuser passages each having a height extending in a spanwise directionbetween the hub and the shroud and extending in a circumferentialdirection between adjacent ones of the first and second partial heightvanes, the plurality of diffuser passages including at least one biasedpassage, the height of the at least one biased passage being greaterthan the height of other ones of the plurality of diffuser passages. 6.The diffuser according to claim 1, wherein the hub includes a hubsurface and the shroud includes a shroud surface, the diffuser furtherincluding at least one elongate flowwise recess located in at least oneof the hub and shroud surfaces.
 7. The diffuser according to claim 6,wherein the at least one elongate flowwise recess includes a pluralityof elongate flowwise recesses having an aperiodic arrangement around acircumference of the diffuser.
 8. The diffuser according to claim 1,wherein the first partial height vanes have a different characteristicthan the second partial height vanes.
 9. The diffuser according to claim8, wherein the different characteristic includes one or more of trailingedge location, chord length, maximum thickness, flowwise shapedistribution, stagger angle, pitch, wedge angle, lean, twist, andleading edge shape.
 10. The diffuser according to claim 1, wherein thediffuser is configured to be operably coupled to a centrifugalcompressor or pump.
 11. The diffuser according to claim 1, wherein atleast two of the vane groupings are immediately adjacent, the first andsecond partial height vanes in the at least two vane groupingspositioned in an alternating and repeating spatial arrangement of (a)one of the first partial height vanes positioned immediately adjacent(b) one of the second partial height vanes, positioned immediatelyadjacent (c) another one of the first partial height vanes.
 12. Thediffuser according to claim 1, wherein at least one of the first partialheight vanes is located at the diffuser inlet, wherein the height of theat least one of the first partial height vanes located at the diffuserinlet is greater than 50% of the passage height at the diffuser inlet.13. The diffuser according to claim 1, wherein the height of all of thefirst partial height vanes is greater than 50% of the passage height atthe diffuser inlet.
 14. The diffuser according to claim 1, wherein atleast one of the first partial height vanes and at least one of thesecond partial height vanes are located at the diffuser inlet, whereinthe height of the at least one of first and second partial height vaneslocated at the diffuser inlet are greater than 50% of the passage heightat the diffuser inlet.
 15. The diffuser according to claim 1, whereinthe height of all of the first partial height vanes and the height ofall of the second partial height vanes are greater than 50% of thepassage height at the diffuser inlet.
 16. The diffuser according toclaim 1, wherein the height of at least one of the first partial heightvanes or at least one of the second partial height vanes is between 15%and 65% of the passage height at the diffuser inlet.
 17. The diffuseraccording to claim 1, wherein the height of at least one of the firstpartial height vanes or at least one of the second partial height vanesis between 5% and 15% of the passage height at the diffuser inlet. 18.The diffuser according to claim 1, wherein the diffuser is configured tobe operably coupled to a mixed flow compressor or pump.
 19. The diffuseraccording to claim 1, wherein a height of the leading edge of at leastone of the first partial height vanes or at least one of the secondpartial height vanes is greater than 50% and less than 65% of thepassage height at the diffuser inlet.
 20. The diffuser according toclaim 1, wherein the diffuser is a single row diffuser, the row of vanesbeing the only row of vanes in the diffuser.
 21. The diffuser accordingto claim 1, wherein each of the first partial height vanes defines anopen space extending between the corresponding first partial height vaneand the shroud.
 22. The diffuser according to claim 21, wherein each ofthe second partial height vanes defines an open space extending betweenthe corresponding second partial height vane and the hub.
 23. Adiffuser, comprising: an inlet, a hub; a shroud; and a row of vanes thatincludes a plurality of first and second partial height vanes, each ofthe plurality of first and second partial height vanes having a leadingedge, each of the first partial height vanes affixed to the hub and eachof the second partial height vanes affixed to the shroud, wherein eachof the first partial height vanes are circumferentially offset fromadjacent ones of the second partial height vanes, and wherein theleading edges of the first partial height vanes or the second partialheight vanes have a height that is greater than 50% and less than 100%of a passage height at the diffuser inlet; wherein the leading edges ofthe first and second partial height vanes are substantially aligned in aflowwise direction; wherein the height of the leading edges of the firstpartial height vanes is different than the height of the leading edgesof the second partial height vanes.
 24. The diffuser according to claim23, wherein the row of vanes includes at least one full height vane. 25.The diffuser according to claim 23, wherein the plurality of first andsecond partial height vanes are positioned around a circumference of thediffuser in an alternating interdigitated arrangement.
 26. The diffuseraccording to claim 23, wherein the plurality of first and second partialheight vanes define a plurality of diffuser passages, the plurality ofdiffuser passages including at least one biased passage having a heightthat is greater than a height of other ones of the plurality of diffuserpassages.
 27. The diffuser according to claim 23, wherein the hubincludes a hub surface and the shroud includes a shroud surface, thediffuser further including at least one elongate flowwise recess locatedin at least one of the hub and shroud surfaces.
 28. The diffuseraccording to claim 27, wherein the at least one elongate flowwise recessincludes a plurality of elongate flowwise recesses having an aperiodicarrangement around a circumference of the diffuser.
 29. The diffuseraccording to claim 23, wherein the first partial height vanes have adifferent characteristic than the second partial height vanes.
 30. Thediffuser according to claim 29, wherein the different characteristicincludes one or more of trailing edge location, chord length, maximumthickness, flowwise shape distribution, stagger angle, pitch, wedgeangle, lean, twist, and leading edge shape.
 31. The diffuser accordingto claim 23, wherein each of the first partial height vanes defines anopen space extending between the corresponding first partial height vaneand the shroud.
 32. The diffuser according to claim 31, wherein each ofthe second partial height vanes defines an open space extending betweenthe corresponding second partial height vane and the hub.
 33. Thediffuser according to claim 23, wherein the diffuser is configured to beoperably coupled to a centrifugal compressor or pump.
 34. The diffuseraccording to claim 23, wherein each of the first and second partialheight vanes are located at the diffuser inlet.
 35. The diffuseraccording to claim 23, wherein the diffuser is configured to be operablycoupled to a mixed flow compressor or pump.
 36. A diffuser, comprising:a hub, and a shroud; and a row of vanes that includes a plurality ofvane groupings each including a first partial height vane affixed to thehub and a second partial height vane circumferentially spaced from thefirst partial height vane and affixed to the shroud; wherein the hubincludes a hub surface and the shroud includes a shroud surface, thediffuser further including a plurality of elongate flowwise recesseslocated in at least one of the hub and shroud surfaces and having anaperiodic arrangement around a circumference of the diffuser.